1. Field of the Invention
The present invention relates to a carrier for a photomask substrate or a silicon wafer employed in manufacturing semiconductor components such as IC, LSI, etc.
2. Description of the Prior Art
A photomask substrate or a silicon wafer is subjected to fine photoetching and contact with operators should be avoided as much as possible. Particular attention is paid when transporting or storing these substrates. Operators try to hold the edges of a substrate to avoid physical contact with its surface.
A photomask substrate of the prior art is 76 to 127 millimeters (mm) square so that it could be transported by holding its edges as described above, requiring no jigs or tools especially designed for the purpose of transportation.
In view of the prior art, the present inventor proposed an invention disclosed in Japanese Utility Model Application No. 59-186600. This invention proposed a carrier comprising a frame in a semi-circular shape or a square having one open side, a handle journaled on the frame in a freely rotatable manner, and supporting rings attached on a frame end and on the inside of the handle so that, when a photomask substrate is held on the peripheral edges thereof with the two supporting rings, the substrate may be held with the rotating force generated downwardly on the ends of the frame.
No transporting jig was required so long as the substrate was small enough to be held at the periphery thereof with only one hand. However, when the substrate becomes as large as 150 to 250 mm square or a disc of 150 to 250 mm diameter, it is difficult to hold it by the edge thereof with only one hand. If both hands are used, the handling of the substrate tends to become unsteady, causing operators to drop it or to touch the surface thereof.
It is difficult to hold a silicon wafer at a single point, for example, by a pair of tweezers. Even if it may be retained, internal distortion due to the weight of the wafer itself often arises and results in a bent or otherwise defective product.
In the above-mentioned device proposed by the present inventor, as the weight of the frame was used to support the substrate, the carrier could effectively transport the substrate which was placed vertically. However, the invention was detrimental in that it was difficult to take out or transport the substrate which was placed horizontally.
The present invention aims to provide a carrier jig which enables operators to transport a photomask substrate or a silicon wafer without touching the surface thereof with fingers and which enables them to take out or transport the substrate whether it is placed vertically or horizontally. The present invention also aims at providing a transporting jig which allows manual operation when a handle is attached, and which also allows the handle thereof to be attached to an industrial robot without any modification.